St Timothy's is one of the UK's top teaching hospitals, home to some of the country's most promising trainee doctors. But beneath its veneer of medical normality lies a secret network of dangerous experiments pushing back the boundaries of science with potentially horrifying consequences in this one-off 60-minute medical horror drama written by Paul Cornell.

Hannah Carter's mother was a consultant at the hospital, but died suddenly a year ago. Grief left Hannah (Claire Foy) teetering on the edge, but following a year off, she's back to resume her training. But Hannah remains fragile, so when she starts glimpsing peculiar events in the hospital and unsettling behavior from her ex-boyfriend and star surgeon Nick (Stephen Campbell Moore), she's unsure what to believe.

Ignoring the pleas of those around her, Hannah puts her sanity on the line to uncover the truth about the hospital.